The invention relates generally to oilfield exploration, production and testing, and more specifically to the conditioning of ferrous alloy elements (tools and equipments and components thereof) into cracking susceptible and fragmentable elements for use downhole in a well.
In the upstream oil and gas industry, the deployment and running of tools and equipments downhole (i.e., down a well, and part of this well may be horizontal) involves considerable time and operating costs. Furthermore, when these tools and equipments are no longer useful to the hydrocarbon exploration, production, or well testing, their retrievals from the wells introduce additional workover time, expenses, and risks (for instance, the improper retrieval of a tool may result in damages to the well completion, itself having well productivity). From a well operator's standpoint, simplifying the well operation by omitting an equipment recovery (fishing) operation offer a cost saving, in addition to technical, safety, and reliability advantages.
In the development of wells for hydrocarbon production, there are tools and equipments, and likewise components of tools and equipments, that are only needed and utilized once, after which they are obsolete and therefore invaluable. An example of fairly large tool falling in the defined category is a perforating gun. A perforating gun is a long tubular product, carrying explosive charges, that is lowered downhole for purposes of penetrating via detonation of these charges and the formation of supersonic jets one or more formations and enable and/or assist in the release of its hydrocarbons. Other examples of downhole tools useful only once are check valves for control or safety devices. Check valves are important elements of well completions because they permit fluids to flow, or pressure to act, in one direction only. A popular type of spring-loaded check valve used today in numerous well completions is the flapper valve. In some instances, flappers include rupture disks that are specifically designed to fracture into harmless fragments at set pressure differential. Other examples of downhole tools that are valuable only once are plugs, and other restrictors, for flow-control and/or zone isolation. Those include bridge plugs and, more generally, may include any other temporary plug (sometimes called dart) set to isolate two distinct parts of a wellbore. In operating a well, it may become extremely desirable to leave a tool or an equipment downhole once it has fulfilled its designated function and reach life time. However, with current tools and well workover practices, there are enormous risks that abandoning tools in the well will interfere with subsequent production and/or intervention operations. On the contrary, having downhole tools and equipments, and likewise components of downhole tools and equipments that predictably break into small and harmless fragments, and optionally disappear over time due to corrosion, will prevent such tool retrieving (fishing) operations and will therefore offer new technical and economical advantages in addition to greater safety and reliability on the rig floor.